The present invention relates to separators for the skimming of liquids, as in gathering or collecting floating materials of various types from the face of a body of liquid into a confined area separated from the remaining face of the liquid.
Separators of various types are well known and widely used in a great number of industrial processes, and include several forms of separators for the skimming of liquids to recover various materials floating on the liquid. However, there are many factors which affect the successful utilization of skimming type separators for specific applications. For example, a separator for skimming oil, dross, or solid materials from a body of water in a controlled industrial process may function very well in that particular application, but be of little or no use in an unsheltered, open body of water with uncontrolled conditions of wind, waves, changing currents, unpredictable oil characteristics, floating trash, and debris of great variety. The need for scavenging oils and other forms of flotage from water for industrial processes, pollution control, and environmental protection purposes is particularly acute, and continues to be a growing problem with additional industrial activity, off-shore oil drilling, and marine transport operations. Through a myriad of sources, various types of oils and other materials frequently become a mixed flotage on open bodies of water. The oils form floating layer films or emulsions of various thickness which tends to spread into a thin layer distributed over a very large surface area, and it is often necessary to scavenge the oil from the face of the body of water as quickly as possible to avoid or minimize extensive pollution. The problem of scavenging unexpected oil spills is often compounded by delays and the oil becoming oxidized or emulsified, to the extent that it has very little film strength to adhere to oleophilic surfaces as frequently used for the selective separation of oil from water. In addition, the presence of other floating materials of a non-liquid or solid nature such as kelp, seaweed, tree leaves, pieces of wood, dead fish and water fowl, floating trash or rubbish, and the like, seriously interferes with the apparatus in attempts to skim the oil from the water, and it is common practice to remove the floating solids by tedious, time consuming methods prior to skimming the oil.
In the prior art and ancient methods of merely controlling the spread of oil on water, bulk materials have been used as flocculants, as weighting materials to sink the oil, oil thickening agents, and as floating absorbent sponge materials, such as straw, milled corn cobs, etc., which were added to and dispersed with the oil. However, if the oil was to be removed from the water, it was necessary to subsequently retrieve the widely scattered bulk material with the adhering or absorbed oil, generally after an extended period of time, great difficulty, and frequent mishaps. A major disadvantage in the use of such bulk materials is the large quantity of bulk material required and the attendant materials handling problems even when the bulk material is capable of being locally regenerated for reuse, which is not possible in many cases. Additionally, environmental protection requirements now often prohibit the use of materials of this type.
In other methods, not using bulk or loose materials as above, various forms of weir skimmers associated with pump means are frequently employed, but have the general disadvantage that increasing quantities of water are removed as the oil film thickness decreases, or as the water surface becomes turbulent due to waves or other disturbances. In addition, floating solid materials easily block the weir apertures, pump, and inlet line. Thus, for scavenging oil layers of lesser thickness, it is generally more advantageous to use rotary skimming separators which either absorbs or adsorbs the oil from the water on a selective basis, as by the use of regeneratable oleophilic conveying materials with which the oil easily adheres under favorable conditions. However, if the oil is in an oxidized or emulsified condition, as may easily occur if the oil is a very thin film or has been on the surface for an extended period of time, the use of oleophilic materials is much less effective and such separators become less selective. In addition, floating solid materials seriously interfere with apparatus of this type, as with the weir type skimmers. Typical rotary type skimming separator prior art for thin oil film scavenging is generally identified in the U.S. Patent Classification 210, as exemplified in the following specific references:
______________________________________ U.S. Patent Inventor ______________________________________ 1,573,085 Meiani 1,860,819 Schamberger 2,470,418 Verner 3,245,539 Earle 3,259,245 Earle 3,487,927 Yahnke 3,539,508 Bulkley, et al 3,546,112 Will, et al 3,576,257 Yates 3,578,585 Yahnke 3,587,860 Ries, Jr. 3,608,727 Grutsch 3,612,277 Van Stavern, et al 3,617,552 Will & Grutsch 3,617,555 Ginsburgh & Will 3,617,556 Cole & Hess 3,643,804 Sharpton ______________________________________
The above references typically comprise rotary or recirculating elements having regenatable oleophilic materials thereon to selectively convey adhering or absorbed oils from water. Other references of interest include those using magnetic particle materials, as exemplified by the following U.S. Pat. Nos.:
______________________________________ 3,635,819 Kaiser 3,717,573 Warren 3,657,119 Turbeville 3,767,571 Lorenc, et al ______________________________________
In the above references, the magnetic particle material is generally used in a bulk form with oleophilic surfactants or absorbent sponge material, and initially used in an unmagnetized state distributed upon the oil. After a period of time, the magnetic particles are retrieved with a magnet means, with the oil adhering to the treated particles or being absorbed within a sponge material attached to and conveyed by the magnetic material under the influence of a magnetic field.